You don't really even know that, as far as his age. Some dated photographs located by Fred Nerks put Stanley Dunham (the grandfather, not the mother) in Hawaii quite a bit earlier than believed. The whole thing could spin off of Obama having been born before statehood, for all we know at this point. It's all been deliberately muddied.
What we do know, is that his eligibility is murky at best due to his having been born to an alien father, and that he's flat out ineligible under several, originalist interpretations. I'm of the opinion that there only is an originalist interpretation, since the language of the Constitution itself precludes anything else.
That’s why I said “approximately.” And I should have said “male baby.”